This invention relates generally to electromechanical switching devices for use in electrical circuits, and more particularly, to a low-profile switching apparatus for use in limited space applications.
In the field of electromechanical switching devices, the use of spring-loaded rotating switches has been recgonized and accepted as an effective way to switch low voltage electrical circuits. Such switches are often employed in various applications in which space limitation is not entirely critical. Typically, the spring-loaded switches of the past have been relatively large requiring substantial space for mounting on a control panel or the like. Such switches of the past have included a body portion combined with a cover portion, the combination providing an outer shell for the spring-loaded switch. Such a switch also included a combination of contacts and terminals joined together to operate as a single unit. An example included a moving contact cup which included a biasing spring mounted within the volume of the contact cup. The biasing spring was employed for completing an electrical circuit between the contact cup and one or more input and output terminals. Additionally, the switch included a push button plunger in mechanical communication with a rotating ratchet mechanism. Both the plunger and the ratchet mechanism were cylindrical in shape with the internal volume of the plunger fashioned for receiving the ratchet mechanism therein.
The push button plunger extended through a cylindrical opening in the body portion of the switch of the prior art. The cylindrical opening or port included a plurality of splines formed in a vertical fashion within the port. Once the switch was assembled, a plurality of protuberances formed on the exterior surface of the plunger, would ride in the spaces between the splines along the inner vertical dimension of the port. Upon operation of the push button plunger, the ratchet mechanism was forced downward against the biasing spring. At the point of ratchet, each of a plurality of protuberances formed on the ratchet mechanism interacted with a ramp portion of each respective spline.
Once the ratchet mechanism passed the apex of the ramp located at the bottom of each spline, the sloped surface located on the top of the ratchet protuberance interfaced with the ramped surface of an individual spline permitting the ratchet protuberance to slide across the spline ramp. This action resulted in the ratchet mechanism rotating to the next adjacent space located between the plurality of splines. Once the ratchet mechanism adopted this posture, the upward force of the biasing spring drove the ratchet mechanism and the plunger to the upper limit of the space between the plurality of splines. Normally, the ratchet mechanism carried the contact cup therewith. Therefore, the operation of the ratchet mechanism caused the contact cup to move with the ratchet permitting the electrical circuit between the contact cup, the biasing spring and a plurality of terminals to be connected or disconnected.
Such an electromechanical switching device of the past was normally mounted upon a chassis by one of two methods. In a first method, part of the external surface or collar of the port through which the push button plunger extended was threaded. The threaded collar was normally passed through a preformed hole in a mounting plate for mating with a complementary threaded nut. Once the nut was threaded onto the collar, the push button switch was securely mounted to the mounting plate and was ready to be wired into the circuitry for control purposes.
A second method of mounting the electromechanical switches of the past included providing a locking ring along the collar of the port which the push button plunger extended through. Thus, a portion of the collar, between the base of the port and the locking ring was sized to be mated with a slot configured into a mounting plate. Installation of the switch in the mounting plate merely required manipulating the body and cover portions of the switch so that the space along the collar was received by the slot in the mounting plate.
Notwithstanding extensive utility, the electromechanical spring-loaded switching devices were not useful in certain limited space applications. Generally, the main problem was the size of the switching device. Certain limited space switching applications such as those existing in printed circuit boards or in miniature battery operated devices did not have sufficient space to employ the previously known electromechanical switches.
High density packaging of printed circuit boards requires that more hardware be fitted onto a single printed circuit board. Such a requirement limits the space dedicated for mounting a switching device and necessitates the development of miniaturized highly efficient current carrying switching devices. Additional examples also include applications in appliance and automotive products which limit the available space for mounting a switching device.
Hence, those concerned with the development and use of electromechanical spring-loaded switching devices in the product development field have long recognized the need for an electromechanical spring-loaded switching device comprised of a miniaturized low-profile switch having a design incorporating low-profile components capable of utilizing either lead-type or tab-type terminals, and including a mounting system suitable for such a low-profile switch while providing similar electrical ratings available in larger switches. The present invention fulfills all of these needs.